Method of simultaneously annealing and descaling tin-plate



UNITED STATES PATENT OFFICE.

ISAAC M. SCOTT, F WI-IEELING, WEST VIRGINIA.

METHOD OF SIMULTANEOUSLY ANNEALING AND DESGALING TIN-PLATE.

No Drawing.

To all whom it may concern Be it known that I, ISAAC M. Soon, a citizen of the United States, residing at Wheeling, in the county of Ohio and State of lVest Vir inia, have invented certain new and useful I mprovements in Methods of Simultaneously Annealing and Descaling Tin- Plate; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to a method of annealing and simultaneously removing oxids of iron from the surface of iron and steel plates and has for its object to improve the processes heretofore proposed.

lVith this and other objects in view the invention consists in the novel steps and combinations of steps constituting the process, all as will be more fully hereinafter disclosed and particularly pointed out in the claims.

In order that the precise invention may be the more clearly understood it is said: It is well known that thin iron or steel plates, commonly lmown as tin plates, have to be subjected to separate annealing and descaling processes before they are ready for the tin bath, and that these separate treatments constitute an important item in the cost of their manufacture. It is the object of this invention, when more particularly stated to reduce this said item of cost by performing the annealing and descaling operations simultaneously. In order to accomplish this. I may lay the plates flat in the annealing boxes and sprinkle by a suitable means, finely divided carbon successively on their surfaces, so that the pile when built up will consist of alternate layers of plates and films of carbon dust; or I may lay the plates fiat in the boxes without any carbon between them, and then turn the boxes and plates on edge and sprinkle carbon dust between. This latter operation is facilitated by the unevennesses between the surfaces of the plates produced by the rolling process. As a further alternative method, I may make a thin paste of finely divided carbon and water, and wash or coat the plates therewith in any suitable manner, as by dipping, flowing the paste over the plates, or otherwise applying it to them, after which the plates are placed in the annealing boxes and passed on into the annealing oven, where they are Specification of Letters Patent. Pate t d N 1 1 Application filed June 30, 1920.

Serial No. 392,987.

heated to a sufficient temperature to cause the carbon to react with the iron oxids, substant ally in accordance with'the following equations I The temperature required must-be not less than say 450 C. to effect a velocity of reaction capable of industrial application, but the temperature may rise to 1000 C. or even somewhathigher, so long as the softening temperature of the iron or steel is not reached. I

After the annealing operation is completed, the plates will be found free from scale and coated in its place with very thin films of iron, which will serve as protectors for the plates against further oxidations. The carbon remaining between the plates is readily removed during the subsequent cleanmg operations, and some of it is found to enter the surfaces of the plates, but notto an objectional extent. After the plates have been thus annealed and descaled, they are put through the other well known process preparatory to the coating with tin in the customary ways.

My invention also includes the annealing or other heat treatment of iron or steel simultaneously with the reduction of iron oxids, by varying the period of cooling, method of quenching, or other treatment during heating or cooling, to realize an industrially useful effect.

In such cases I prefer to embed the shaped metal in pulverized dry coke, charcoal, or other forms of commercial carbon, or carbonaceous matter; but I may also dip such metal shapes in a finely divided carbon or carbonaceous material suspended in water, oil, or other liquid vehicle, in order to cover such shapes when in forms to permit such a procedure. Such shapes, when in the forms of sheets, plates, etc, may be passed through rolls, or other coating applying means, which are constantly supplied with a carbonaceous matter in the form of a thick paste or emulslon. In such cases the treatment is somewhat analogous to the inking of type faces or by electric means Within the furnace chamber. Said process may also be carried out in an atmosphere of ordinary fuel combustion products, or in a vacuum, or in an atmosphere composed of inert gases, such as nitrogen, hydrogen, carbon monoXid, natural gas, etc., or in other gases Which cannot cause oxidation of the metal. Said process, also may be readily carried out under conditions capable of controlling or regulating the mixture and concentration of such gases.

My process is likewise carried out at such temperatures and under such times of treatment as will preclude any serious carburization of the metal shapes, unless such carburization is desired.

What I claim is s 1. The process of simultaneously annealing and descaling tin plate which consists in packingsaid plate in annealing boxes With carbonaceous material between them; and then subjecting said plates to annealing temperatures suflicient to reduce the scale prescnt, but insufficient to carbonize the plate to a substantial extent, substantially as described.

2. The process of simultaneously annealing and descaling tin plate, Which consists in placing said plate into annealing boxes; placing finely divided carbon between the individual plates; and passing the packs of plates thus formed through the usual annealing process, substantially as described.

3. The process of simultaneously annealing and descaling iron and steel forms which consists in coating the surfaces of said forms with a Wet carbonaceous material, and then subjecting the coated forms in an atmosphere of reducing gasto the action of annealing temperatures sufficient to reduce the scale present but insufiicient to materially carburize said. forms, substantially as described.

In testimony whereof I afliX my signature.

ISAAC M. SCOTT. 

